[Mesa-dev] [PATCH] i965/miptree: Initialize mcs buffer only until clear color

[Jason Ekstrand]

On Fri, Apr 6, 2018 at 8:22 AM, Rafael Antognolli <
rafael.antognolli at intel.com> wrote:

> On Fri, Apr 06, 2018 at 06:07:52PM +0300, Topi Pohjolainen wrote:
> > Otherwise even the clear color gets initialised to 0xFF. This
> > allows enabling of color fast clears on ICL without regressing
> > multisampling tests.
> >
> > CC: Rafael Antognolli <rafael.antognolli at intel.com>
> > CC: Jason Ekstrand <jason at jlekstrand.net>
> > CC: Nanley Chery <nanley.g.chery at intel.com>
> > Signed-off-by: Topi Pohjolainen <topi.pohjolainen at intel.com>
> > ---
> >  src/mesa/drivers/dri/i965/intel_mipmap_tree.c | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> > index 89074a6..25f901d 100644
> > --- a/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> > +++ b/src/mesa/drivers/dri/i965/intel_mipmap_tree.c
> > @@ -1680,7 +1680,12 @@ intel_miptree_init_mcs(struct brw_context *brw,
> >        return;
> >     }
> >     void *data = map;
> > -   memset(data, init_value, mt->mcs_buf->size);
> > +
> > +   /* Only initialize until clear color (if present). */
> > +   const unsigned aux_size = mt->mcs_buf->clear_color_offset ?
> > +                                mt->mcs_buf->clear_color_offset :
> > +                                mt->mcs_buf->size;
> > +   memset(data, init_value, aux_size);
>

Why not just use mt->mcs_buf->aux_surf.size?

Also, I think we probably want to memset the clear color to 0 in case we
get a recycled BO with unknown garbage in the clear value.


> Hmm... that's a good catch, and I think we definitely should not
> overwrite the clear color here.
>
> However, the initial value of the clear color shouldn't matter, right? I
> think there might still be a bug hidden somewhere...
>
> Regardless of that, this patch is
>
> Reviewed-by: Rafael Antognolli <rafael.antognolli at intel.com>
>
> >     brw_bo_unmap(mt->mcs_buf->bo);
> >  }
> >
> > --
> > 2.7.4
> >
>
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